Garver revealed yesterday that she is leaving NASA after four years as the agency's number two official. Today, Bolden called her an "indispensable partner" and a "remarkable leader who has consistently shown great vision and commitment to NASA and the aerospace industry."

Holdren, who is director of the White House Office of Science and Technology Policy (OSTP), thanked her on behalf of President Obama and himself for her "leadership, dedication and work on behalf of the American people..."

Garver reportedly is joining the Air Line Pilots Association. Her resignation from NASA is effective September 6.